Velocity resolution

Figure 4. 2.10 shows the power of using MRI to determine viscosity. In this figure, the radial resolution of the MRI has been varied from 200 pm to 1 mm while the velocity resolution has remained constant at 8iv = 2.2 mm s-1. The most important conclusions to draw from this are two-fold. Firstly, the effect of the radial resolution is small. On the scale shown in Figure 4. 2.10, it is almost impossible to discern any effect whatsoever. Qualitatively, the net effect of changing the radial... 

Fig. 4.2.14 Dimensionless correlation between the minimum shear rate at which the shear viscosity can be obtained via MRI, ymjn and the velocity resolution, These data were obtained using an aqueous polyacrylamide solution at two different volume flow rates, or mean velocities, w.

The fragment recoil velocity resolution depends on the divergence of the molecular beam, molecular beam velocity distribution in the direction of the molecular beam axis, and the distance of fragments expanded in the velocity axis of the two-dimensional detector. If the divergence of the molecular beam is small and the fragment recoil velocity is much larger than the velocity difference of parent molecules, the recoil velocity resolution can be simply expressed as AV/V = s/L, where L is the length of expansion of... 

Radar range velocity measurement and range velocity resolution... 

The intensity of the He beam of the apparatus shown in Fig. 5 collimated to 0.4° full width at half maximum (FWHM) is typically 1010 singlets/sec (or 3 -1014 atoms/sec sr) and 1.5 -109 triplets/sec for beam energies of 66 to 350 meV and about 20% of this value at 16.5 meV (liquid-nitrogen-cooled nozzle). The triplet intensity can be increased at the expense of a poorer velocity resolution by a lower electron-acceleration voltage. 

Figure 18 shows differential cross sections measured using the helium plasma jet described in Section III.A.6. It is surprising that so much structure is still resolved, even though the velocity resolution of the beam is only 30%. No fit has so far been attempted for these data. 

In both neutron and y-ray detection, the shielding of the detector is extremely important. Especially in the neutron detection measurements, the long target-to-detector distance (2-4 in) which is required to obtain velocity resolution via the neutron TOF technique means many more neutrons are produced than are actually scattered from the sample and then detected. These extraneous neutrons create a disastrous background unless the detector is adequately shielded. We have accomplished this with a large cylindrical shield which contains a lead cavity surrounded by Li2C03 loaded paraffin. The entrance collimator has steel and lead liners the main detector shield weighs about 2000 kg (see B in Fig. 1). 

Utilization of both ion and neutral beams for such studies has been reported. Toennies [150] has performed measurements on the inelastic collision cross section for transitions between specified rotational states using a molecular beam apparatus. T1F molecules in the state (J, M) were separated out of a beam traversing an electrostatic four-pole field by virtue of the second-order Stark effect, and were directed into a noble-gas-filled scattering chamber. Molecules which were scattered by less than were then collected in a second four-pole field, and were analyzed for their final rotational state. The beam originated in an effusive oven source and was chopped to obtain a velocity resolution Avjv of about 7 %. The velocity change due to the inelastic encounters was about 0.3 %. Transition probabilities were calculated using time-dependent perturbation theory and the straight-line trajectory approximation. The interaction potential was taken to be purely attractive ... 

Temperature Seabird/SBE-4-01 Platinum resistance thermometer 0.01 °C 70 ms at 1-m/s water velocity Resolution 0.0005 °C at 12 samples/s... 

These systems have been carefully studied in a series of high resolution experiments at thermal energies. A velocity resolution of about 2 % (FWHM) and an angular resolution of about 0-3° provided the possibility to resolve... 

---